If a competitive inhibitor is added to an enzymatic reaction that is proceeding at its optimum pH and temperature, the reaction rate will slow down. This is because the competitive inhibitor binds to the active site of the enzyme, preventing the substrate from binding. As a result, the enzyme is unable to catalyze the reaction, and the reaction rate decreases.

The extent to which the reaction rate slows down depends on the concentration of the competitive inhibitor. The higher the concentration of the inhibitor, the greater the inhibition of the reaction. Eventually, at a high enough concentration of inhibitor, the reaction rate will be completely inhibited.

Competitive inhibition can be overcome by increasing the concentration of the substrate. This is because the substrate and the inhibitor compete for binding to the active site of the enzyme. If the substrate concentration is increased, there will be more substrate molecules available to bind to the enzyme, and the chances of the inhibitor binding to the enzyme will be reduced. As a result, the reaction rate will increase.

Competitive inhibition is a common type of enzyme inhibition. It is important to understand how competitive inhibitors work in order to design drugs and other compounds that can inhibit enzymes.